/Engine/Source/Runtime/MeshConversion/Public/MeshDescriptionBuilder.h
Set the UV of a vertex instance. Note: this generally shouldn't be called directly because it alters the instance UVs but not the shared UVs When setting UVs use AppendUVTriangle
void SetInstanceUV ( const [FVertexInstanceID](API\Runtime\MeshDescription\FVertexInstanceID) & InstanceID, const FVector2D & InstanceUV, int32 UVLayerIndex )